OSPF route summarization

[rreed2010]

I'm trying to use a summary-address between area 0 & area 90.  My ABR is connected to multiple other areas.  If I use "area 0 range 10.0.0.0 255.0.0.0" I'd like the summary address to only be injected to area 90 and no others.  Does anyone know if it's possible to limit this to only a single area?  Unfortunately, I cannot use stub's or NSSAs as there is a static default route that is being used. 

[paul driver]

Hello
What  are you trying to summarise internal or external routes

On the ABR of area 90 
router ospf x
area 90 range 10.0.0.0 255.0.0.0 advertise  < internal 

On the ASBR of area 90 that originates  type 5 lsa's <  external 
router ospf x 
summary address 10.0.0.0 255.0.0.0 

[Richard Burts · Accepted solution]

Paul

Perhaps my reading of the original post is a bit different from yours. My understanding was that the routes to be summarized exist in area 0 and they want to advertise the summary to area 90 but not to other areas. Your suggestions seem to reflect an understanding that the routes exist in area 90. Perhaps the original poster can provide clarification?

Assuming that area 90 is a normal OSPF area and that there are other normal OSPF areas connected to area 0 it is quite challenging to have the OSPF process do summarization for one area but not for other areas. The solution that occurs to me that could accomplish this would be to configure a second OSPF process which would connect to area 90. You could redistribute routes from the first OSPF process to the second process and summarize them for advertisement into area 90. And you would need to redistribute the routes learned by the second process from area 90 into the first process. It is a bit messy and it does change some routes that would have been internal into external. But it accomplishes the requirement of sending summary routes into only one of the several normal OSPF areas.

HTH

Rick

[paul driver]

Hello Richard

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@Richard Burts wrote:

Your suggestions seem to reflect an understanding that the routes exist in area 90.

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Correct Richard that was my understanding of the OP, hence i provide two examples regards area 0 intra-area/external routes from area 90

[rreed2010]

Richard,
You are correct. I am attempting to summarize routes in Area 0. I never considered running a separate routing process for OSPF. I will lab this out and see if I can get it to work. Thank you for your response.

[Richard Burts]

I am glad that my suggestions have been helpful. As I said it is a bit messy and it does have some impacts (which might or might not matter - depending on things in your network which we do not know). But it should achieve your objective of summarization into one OSPF area while not summarizing into other OSPF areas. Thank you for marking this question as solved. This will help other participants in the community to recognize discussions which have useful information. This has been an interesting question and I believe that some others may be interested in it.

HTH

Rick